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  <div class="section" id="importing-modules">
<span id="importing"></span><h1>Importing Modules<a class="headerlink" href="#importing-modules" title="Permalink to this headline">¶</a></h1>
<dl class="cfunction">
<dt id="PyImport_ImportModule">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ImportModule</tt><big>(</big>const char<em> *name</em><big>)</big><a class="headerlink" href="#PyImport_ImportModule" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-33">This is a simplified interface to <a title="PyImport_ImportModuleEx" class="reference internal" href="#PyImport_ImportModuleEx"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModuleEx</span></tt></a> below,
leaving the <em>globals</em> and <em>locals</em> arguments set to <em>NULL</em> and <em>level</em> set
to 0.  When the <em>name</em>
argument contains a dot (when it specifies a submodule of a package), the
<em>fromlist</em> argument is set to the list <tt class="docutils literal"><span class="pre">['*']</span></tt> so that the return value is the
named module rather than the top-level package containing it as would otherwise
be the case.  (Unfortunately, this has an additional side effect when <em>name</em> in
fact specifies a subpackage instead of a submodule: the submodules specified in
the package&#8217;s <tt class="docutils literal"><span class="pre">__all__</span></tt> variable are  loaded.)  Return a new reference to the
imported module, or <em>NULL</em> with an exception set on failure.  Before Python 2.4,
the module may still be created in the failure case &#8212; examine <tt class="docutils literal"><span class="pre">sys.modules</span></tt>
to find out.  Starting with Python 2.4, a failing import of a module no longer
leaves the module in <tt class="docutils literal"><span class="pre">sys.modules</span></tt>.</p>
<p>
<span class="versionmodified">Changed in version 2.4: </span>failing imports remove incomplete module objects.</p>
<p>
<span class="versionmodified">Changed in version 2.6: </span>always use absolute imports</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ImportModuleNoBlock">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ImportModuleNoBlock</tt><big>(</big>const char<em> *name</em><big>)</big><a class="headerlink" href="#PyImport_ImportModuleNoBlock" title="Permalink to this definition">¶</a></dt>
<dd><p>This version of <a title="PyImport_ImportModule" class="reference internal" href="#PyImport_ImportModule"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModule</span></tt></a> does not block. It&#8217;s intended
to be used in C functions that import other modules to execute a function.
The import may block if another thread holds the import lock. The function
<a title="PyImport_ImportModuleNoBlock" class="reference internal" href="#PyImport_ImportModuleNoBlock"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModuleNoBlock</span></tt></a> never blocks. It first tries to fetch
the module from sys.modules and falls back to <a title="PyImport_ImportModule" class="reference internal" href="#PyImport_ImportModule"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModule</span></tt></a>
unless the lock is held, in which case the function will raise an
<a title="exceptions.ImportError" class="reference external" href="../library/exceptions.html#exceptions.ImportError"><tt class="xref docutils literal"><span class="pre">ImportError</span></tt></a>.</p>
<p>
<span class="versionmodified">New in version 2.6.</span></p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ImportModuleEx">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ImportModuleEx</tt><big>(</big>char<em> *name</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *globals</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *locals</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *fromlist</em><big>)</big><a class="headerlink" href="#PyImport_ImportModuleEx" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-34">Import a module.  This is best described by referring to the built-in Python
function <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a>, as the standard <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a> function calls
this function directly.</p>
<p>The return value is a new reference to the imported module or top-level package,
or <em>NULL</em> with an exception set on failure (before Python 2.4, the module may
still be created in this case).  Like for <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a>, the return value
when a submodule of a package was requested is normally the top-level package,
unless a non-empty <em>fromlist</em> was given.</p>
<p>
<span class="versionmodified">Changed in version 2.4: </span>failing imports remove incomplete module objects.</p>
<p>
<span class="versionmodified">Changed in version 2.6: </span>The function is an alias for <a title="PyImport_ImportModuleLevel" class="reference internal" href="#PyImport_ImportModuleLevel"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModuleLevel</span></tt></a> with
-1 as level, meaning relative import.</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ImportModuleLevel">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ImportModuleLevel</tt><big>(</big>char<em> *name</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *globals</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *locals</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *fromlist</em>, int<em> level</em><big>)</big><a class="headerlink" href="#PyImport_ImportModuleLevel" title="Permalink to this definition">¶</a></dt>
<dd><p>Import a module.  This is best described by referring to the built-in Python
function <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a>, as the standard <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a> function calls
this function directly.</p>
<p>The return value is a new reference to the imported module or top-level package,
or <em>NULL</em> with an exception set on failure.  Like for <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a>,
the return value when a submodule of a package was requested is normally the
top-level package, unless a non-empty <em>fromlist</em> was given.</p>
<p>
<span class="versionmodified">New in version 2.5.</span></p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_Import">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_Import</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *name</em><big>)</big><a class="headerlink" href="#PyImport_Import" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-35">This is a higher-level interface that calls the current &#8220;import hook function&#8221;.
It invokes the <a title="__import__" class="reference external" href="../library/functions.html#__import__"><tt class="xref docutils literal"><span class="pre">__import__()</span></tt></a> function from the <tt class="docutils literal"><span class="pre">__builtins__</span></tt> of the
current globals.  This means that the import is done using whatever import hooks
are installed in the current environment, e.g. by <a title="Basic restricted execution framework. (deprecated)" class="reference external" href="../library/rexec.html#module-rexec"><tt class="xref docutils literal"><span class="pre">rexec</span></tt></a> or <tt class="xref docutils literal"><span class="pre">ihooks</span></tt>.</p>
<p>
<span class="versionmodified">Changed in version 2.6: </span>always use absolute imports</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ReloadModule">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ReloadModule</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *m</em><big>)</big><a class="headerlink" href="#PyImport_ReloadModule" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-36">Reload a module.  This is best described by referring to the built-in Python
function <a title="reload" class="reference external" href="../library/functions.html#reload"><tt class="xref docutils literal"><span class="pre">reload()</span></tt></a>, as the standard <a title="reload" class="reference external" href="../library/functions.html#reload"><tt class="xref docutils literal"><span class="pre">reload()</span></tt></a> function calls this
function directly.  Return a new reference to the reloaded module, or <em>NULL</em>
with an exception set on failure (the module still exists in this case).</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_AddModule">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_AddModule</tt><big>(</big>const char<em> *name</em><big>)</big><a class="headerlink" href="#PyImport_AddModule" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><p>Return the module object corresponding to a module name.  The <em>name</em> argument
may be of the form <tt class="docutils literal"><span class="pre">package.module</span></tt>. First check the modules dictionary if
there&#8217;s one there, and if not, create a new one and insert it in the modules
dictionary. Return <em>NULL</em> with an exception set on failure.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">This function does not load or import the module; if the module wasn&#8217;t already
loaded, you will get an empty module object. Use <a title="PyImport_ImportModule" class="reference internal" href="#PyImport_ImportModule"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModule</span></tt></a>
or one of its variants to import a module.  Package structures implied by a
dotted name for <em>name</em> are not created if not already present.</p>
</div>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ExecCodeModule">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_ExecCodeModule</tt><big>(</big>char<em> *name</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *co</em><big>)</big><a class="headerlink" href="#PyImport_ExecCodeModule" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-37">Given a module name (possibly of the form <tt class="docutils literal"><span class="pre">package.module</span></tt>) and a code object
read from a Python bytecode file or obtained from the built-in function
<a title="compile" class="reference external" href="../library/functions.html#compile"><tt class="xref docutils literal"><span class="pre">compile()</span></tt></a>, load the module.  Return a new reference to the module object,
or <em>NULL</em> with an exception set if an error occurred.  Before Python 2.4, the
module could still be created in error cases.  Starting with Python 2.4, <em>name</em>
is removed from <a title="sys.modules" class="reference external" href="../library/sys.html#sys.modules"><tt class="xref docutils literal"><span class="pre">sys.modules</span></tt></a> in error cases, and even if <em>name</em> was already
in <a title="sys.modules" class="reference external" href="../library/sys.html#sys.modules"><tt class="xref docutils literal"><span class="pre">sys.modules</span></tt></a> on entry to <a title="PyImport_ExecCodeModule" class="reference internal" href="#PyImport_ExecCodeModule"><tt class="xref docutils literal"><span class="pre">PyImport_ExecCodeModule</span></tt></a>.  Leaving
incompletely initialized modules in <a title="sys.modules" class="reference external" href="../library/sys.html#sys.modules"><tt class="xref docutils literal"><span class="pre">sys.modules</span></tt></a> is dangerous, as imports of
such modules have no way to know that the module object is an unknown (and
probably damaged with respect to the module author&#8217;s intents) state.</p>
<p>This function will reload the module if it was already imported.  See
<a title="PyImport_ReloadModule" class="reference internal" href="#PyImport_ReloadModule"><tt class="xref docutils literal"><span class="pre">PyImport_ReloadModule</span></tt></a> for the intended way to reload a module.</p>
<p>If <em>name</em> points to a dotted name of the form <tt class="docutils literal"><span class="pre">package.module</span></tt>, any package
structures not already created will still not be created.</p>
<p>
<span class="versionmodified">Changed in version 2.4: </span><em>name</em> is removed from <a title="sys.modules" class="reference external" href="../library/sys.html#sys.modules"><tt class="xref docutils literal"><span class="pre">sys.modules</span></tt></a> in error cases.</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_GetMagicNumber">
long <tt class="descname">PyImport_GetMagicNumber</tt><big>(</big><big>)</big><a class="headerlink" href="#PyImport_GetMagicNumber" title="Permalink to this definition">¶</a></dt>
<dd>Return the magic number for Python bytecode files (a.k.a. <tt class="docutils literal"><span class="pre">.pyc</span></tt> and
<tt class="docutils literal"><span class="pre">.pyo</span></tt> files).  The magic number should be present in the first four bytes
of the bytecode file, in little-endian byte order.</dd></dl>

<dl class="cfunction">
<dt id="PyImport_GetModuleDict">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_GetModuleDict</tt><big>(</big><big>)</big><a class="headerlink" href="#PyImport_GetModuleDict" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><p>Return the dictionary used for the module administration (a.k.a.
<tt class="docutils literal"><span class="pre">sys.modules</span></tt>).  Note that this is a per-interpreter variable.</p>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_GetImporter">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyImport_GetImporter</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *path</em><big>)</big><a class="headerlink" href="#PyImport_GetImporter" title="Permalink to this definition">¶</a></dt>
<dd><p>Return an importer object for a <a title="sys.path" class="reference external" href="../library/sys.html#sys.path"><tt class="xref docutils literal"><span class="pre">sys.path</span></tt></a>/<tt class="xref docutils literal"><span class="pre">pkg.__path__</span></tt> item
<em>path</em>, possibly by fetching it from the <a title="sys.path_importer_cache" class="reference external" href="../library/sys.html#sys.path_importer_cache"><tt class="xref docutils literal"><span class="pre">sys.path_importer_cache</span></tt></a>
dict.  If it wasn&#8217;t yet cached, traverse <a title="sys.path_hooks" class="reference external" href="../library/sys.html#sys.path_hooks"><tt class="xref docutils literal"><span class="pre">sys.path_hooks</span></tt></a> until a hook
is found that can handle the path item.  Return <tt class="xref docutils literal"><span class="pre">None</span></tt> if no hook could;
this tells our caller it should fall back to the builtin import mechanism.
Cache the result in <a title="sys.path_importer_cache" class="reference external" href="../library/sys.html#sys.path_importer_cache"><tt class="xref docutils literal"><span class="pre">sys.path_importer_cache</span></tt></a>.  Return a new reference
to the importer object.</p>
<p>
<span class="versionmodified">New in version 2.6.</span></p>
</dd></dl>

<dl class="cfunction">
<dt id="_PyImport_Init">
void <tt class="descname">_PyImport_Init</tt><big>(</big><big>)</big><a class="headerlink" href="#_PyImport_Init" title="Permalink to this definition">¶</a></dt>
<dd>Initialize the import mechanism.  For internal use only.</dd></dl>

<dl class="cfunction">
<dt id="PyImport_Cleanup">
void <tt class="descname">PyImport_Cleanup</tt><big>(</big><big>)</big><a class="headerlink" href="#PyImport_Cleanup" title="Permalink to this definition">¶</a></dt>
<dd>Empty the module table.  For internal use only.</dd></dl>

<dl class="cfunction">
<dt id="_PyImport_Fini">
void <tt class="descname">_PyImport_Fini</tt><big>(</big><big>)</big><a class="headerlink" href="#_PyImport_Fini" title="Permalink to this definition">¶</a></dt>
<dd>Finalize the import mechanism.  For internal use only.</dd></dl>

<dl class="cfunction">
<dt id="_PyImport_FindExtension">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">_PyImport_FindExtension</tt><big>(</big>char<em> *</em>, char<em> *</em><big>)</big><a class="headerlink" href="#_PyImport_FindExtension" title="Permalink to this definition">¶</a></dt>
<dd>For internal use only.</dd></dl>

<dl class="cfunction">
<dt id="_PyImport_FixupExtension">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">_PyImport_FixupExtension</tt><big>(</big>char<em> *</em>, char<em> *</em><big>)</big><a class="headerlink" href="#_PyImport_FixupExtension" title="Permalink to this definition">¶</a></dt>
<dd>For internal use only.</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ImportFrozenModule">
int <tt class="descname">PyImport_ImportFrozenModule</tt><big>(</big>char<em> *name</em><big>)</big><a class="headerlink" href="#PyImport_ImportFrozenModule" title="Permalink to this definition">¶</a></dt>
<dd>Load a frozen module named <em>name</em>.  Return <tt class="docutils literal"><span class="pre">1</span></tt> for success, <tt class="docutils literal"><span class="pre">0</span></tt> if the
module is not found, and <tt class="docutils literal"><span class="pre">-1</span></tt> with an exception set if the initialization
failed.  To access the imported module on a successful load, use
<a title="PyImport_ImportModule" class="reference internal" href="#PyImport_ImportModule"><tt class="xref docutils literal"><span class="pre">PyImport_ImportModule</span></tt></a>.  (Note the misnomer &#8212; this function would
reload the module if it was already imported.)</dd></dl>

<dl class="ctype">
<dt id="_frozen">
struct <tt class="descname">_frozen</tt><a class="headerlink" href="#_frozen" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-38">This is the structure type definition for frozen module descriptors, as
generated by the <strong>freeze</strong> utility (see <tt class="docutils literal"><span class="pre">Tools/freeze/</span></tt> in the
Python source distribution).  Its definition, found in <tt class="docutils literal"><span class="pre">Include/import.h</span></tt>,
is:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">struct</span> <span class="n">_frozen</span> <span class="p">{</span>
    <span class="kt">char</span> <span class="o">*</span><span class="n">name</span><span class="p">;</span>
    <span class="kt">unsigned</span> <span class="kt">char</span> <span class="o">*</span><span class="n">code</span><span class="p">;</span>
    <span class="kt">int</span> <span class="n">size</span><span class="p">;</span>
<span class="p">};</span>
</pre></div>
</div>
</dd></dl>

<dl class="cvar">
<dt id="PyImport_FrozenModules">
struct <a title="_frozen" class="reference internal" href="#_frozen">_frozen</a>* <tt class="descname">PyImport_FrozenModules</tt><a class="headerlink" href="#PyImport_FrozenModules" title="Permalink to this definition">¶</a></dt>
<dd>This pointer is initialized to point to an array of <tt class="xref docutils literal"><span class="pre">struct</span> <span class="pre">_frozen</span></tt>
records, terminated by one whose members are all <em>NULL</em> or zero.  When a frozen
module is imported, it is searched in this table.  Third-party code could play
tricks with this to provide a dynamically created collection of frozen modules.</dd></dl>

<dl class="cfunction">
<dt id="PyImport_AppendInittab">
int <tt class="descname">PyImport_AppendInittab</tt><big>(</big>char<em> *name</em>, void<em> (*initfunc)(void)</em><big>)</big><a class="headerlink" href="#PyImport_AppendInittab" title="Permalink to this definition">¶</a></dt>
<dd>Add a single module to the existing table of built-in modules.  This is a
convenience wrapper around <a title="PyImport_ExtendInittab" class="reference internal" href="#PyImport_ExtendInittab"><tt class="xref docutils literal"><span class="pre">PyImport_ExtendInittab</span></tt></a>, returning <tt class="docutils literal"><span class="pre">-1</span></tt> if
the table could not be extended.  The new module can be imported by the name
<em>name</em>, and uses the function <em>initfunc</em> as the initialization function called
on the first attempted import.  This should be called before
<a title="Py_Initialize" class="reference external" href="init.html#Py_Initialize"><tt class="xref docutils literal"><span class="pre">Py_Initialize</span></tt></a>.</dd></dl>

<dl class="ctype">
<dt id="_inittab">
struct <tt class="descname">_inittab</tt><a class="headerlink" href="#_inittab" title="Permalink to this definition">¶</a></dt>
<dd><p>Structure describing a single entry in the list of built-in modules.  Each of
these structures gives the name and initialization function for a module built
into the interpreter.  Programs which embed Python may use an array of these
structures in conjunction with <a title="PyImport_ExtendInittab" class="reference internal" href="#PyImport_ExtendInittab"><tt class="xref docutils literal"><span class="pre">PyImport_ExtendInittab</span></tt></a> to provide
additional built-in modules.  The structure is defined in
<tt class="docutils literal"><span class="pre">Include/import.h</span></tt> as:</p>
<div class="highlight-c"><div class="highlight"><pre><span class="k">struct</span> <span class="n">_inittab</span> <span class="p">{</span>
    <span class="kt">char</span> <span class="o">*</span><span class="n">name</span><span class="p">;</span>
    <span class="kt">void</span> <span class="p">(</span><span class="o">*</span><span class="n">initfunc</span><span class="p">)(</span><span class="kt">void</span><span class="p">);</span>
<span class="p">};</span>
</pre></div>
</div>
</dd></dl>

<dl class="cfunction">
<dt id="PyImport_ExtendInittab">
int <tt class="descname">PyImport_ExtendInittab</tt><big>(</big>struct <a title="_inittab" class="reference internal" href="#_inittab">_inittab</a><em> *newtab</em><big>)</big><a class="headerlink" href="#PyImport_ExtendInittab" title="Permalink to this definition">¶</a></dt>
<dd>Add a collection of modules to the table of built-in modules.  The <em>newtab</em>
array must end with a sentinel entry which contains <em>NULL</em> for the <tt class="xref docutils literal"><span class="pre">name</span></tt>
field; failure to provide the sentinel value can result in a memory fault.
Returns <tt class="docutils literal"><span class="pre">0</span></tt> on success or <tt class="docutils literal"><span class="pre">-1</span></tt> if insufficient memory could be allocated to
extend the internal table.  In the event of failure, no modules are added to the
internal table.  This should be called before <a title="Py_Initialize" class="reference external" href="init.html#Py_Initialize"><tt class="xref docutils literal"><span class="pre">Py_Initialize</span></tt></a>.</dd></dl>

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